Byte based (de)serialization in Java?

Question

I want to try abusing Java classes as structures and for that I'm wondering if it is possible to serialize a byte array to a class and other way around.

So if I have a class like this:

public class Handshake
{
    byte command;
    byte error;
    short size;
    int major;
    int ts;
    char[] secret; // aligned size = 32 bytes
}

Is there an easy way (without having to manually read bytes and fill out the class which requires 3 times as much code) to deserialize a set of bytes into this class? I know that Java doesn't have structs but I'm wondering if it is possible to simplify the serialization process so it does it automatically. The bytes are not from Java's serializer, they are just aligned bytes derived from C structs.

Maybe I'm missing something, but what exactly is the difference between this question and your previous one? — Joachim Sauer
– Joachim Sauer, Commented Aug 1, 2011 at 14:35
This is treading awfully close to being a duplicate of your own questions - stackoverflow.com/questions/6891663/…. — Perception
– Perception, Commented Aug 1, 2011 at 14:36
I'm still trying to find out if I can achieve this sort of thing in Java. — krb
– krb, Commented Aug 1, 2011 at 14:37

Michael Borgwardt · Accepted Answer · 2011-08-01 14:46:55Z

2

The bytes are not from Java's serializer, they are just aligned bytes derived from C structs.

Bad idea. It can break as soon as someone compiles that code on a different platform, using a different compiler or settings, etc.

Much better: use a standardized binary interface with implementations in Java and C++ like ASN.1 or Google's Protocol Buffers.

answered Aug 1, 2011 at 14:46

Michael Borgwardt

347k81 gold badges491 silver badges726 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

krb Over a year ago

The client's protocol is well defined and isn't going to be changed in the near future.

user207421 Over a year ago

@Nick Brooks that implies that it must be defined some way other than via C structs.

Peter Lawrey · Accepted Answer · 2011-08-01 14:38:09Z

0

You can write a library to do the deserializtion using reflection. This may result in more code being required, but may suit your needs. It worth nothing that char in Java 16-bit rather than 8 bit and a char[] is a separate Object, unlike in C.

In short you can write a library which reads this data without touching the Handshake class. Only you can decide if this is actually easier than adding a method or two to the handshake class..

answered Aug 1, 2011 at 14:38

Peter Lawrey

535k83 gold badges770 silver badges1.2k bronze badges

Comments

Pablo Grisafi · Accepted Answer · 2011-08-01 15:34:54Z

0

Do not do that! I will break sooner or later. Use some binary serialization format, like [Hessian][1], which supports both java and C++ (I'm not aware of anything that works on plain C)
Also remember C does not force size for int's or long's, they are platform dependent. So if you must use C, and you are forced to write your own library, be very careful.

answered Aug 1, 2011 at 15:34

Pablo Grisafi

4,9321 gold badge21 silver badges30 bronze badges

Collectives™ on Stack Overflow

Byte based (de)serialization in Java?

3 Answers 3

2 Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

2 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related